A physiological study of Macleod's syndrome.

Seven patients with Macleod's syndrome of abnormal transradiancy of one lung have been investigated with special reference to regional lung function. The principal abnormality was found to be obstruction of the airways. This was severe in the affected lung but was often present in the other lung as well. Five of the seven patients suffered from chronic bronchitis, as judged by the M.R.C. questionnaire. Although functional impairment of the affected lung was severe, it was by no means uniformly distributed there. There was evidence of defective gas transfer in all the patients who complained of breathlessness on exertion; the blood gases were only slightly abnormal at rest, and hypercapnia, in particular, was not a feature. During exercise arterial oxygen tensions tended to fall. Clinically it was found that the stethoscope gave a rough guide to the extent of regional underventilation and that radiographs were useful for judging the distribution of blood within the lung. We conclude that treatment should be conservative, directed towards avoidance of environments and habits likely to cause or exaggerate airways obstruction or bronchitis.